All‐Solution‐Processed Metal Oxide/Chalcogenide Hybrid Full‐Color Phototransistors with Multistacked Functional Layers and Composition‐Gradient Heterointerface

Abstract For the development of cost‐effective, ultrasensitive, fast dynamic, and full‐color photodetection platforms, an all‐solution‐processed metal oxide/chalcogenide semiconductor hybrid‐structure‐based visible‐light phototransistor with (i) multistacked functional materials, (ii) a chemically stable solution‐based construction, and (iii) defect‐suppressed composition‐gradient heterointerfaces is proposed. Herein, the functional multistacked structure (a‐ZTO/cc‐CdS/a‐ZTO) consists of high‐mobility amorphous zinc tin oxide (ZTO) (a‐ZTO bottom), a high‐efficiency coarsened crystalline CdS (cc‐CdS) visible‐light absorber, and defective surface passivation a‐ZTO (top) to boost photosensitivity via efficient generation/transport and spontaneous separation/confinement of photocarriers. Chemically stable solution‐based multistacking is achieved via careful choice of chemically durable oxide and chalcogenide semiconductors (Sn‐eqi ZTO and CdS). The composition‐gradient heterointerfaces formed near ZTO/CdS and CdS/ZTO junctions via thermally activated healing processes provide instantaneous photoresponse and full‐color sensing performance. Finally, the all‐solution‐processed a‐ZTO/cc‐CdS/a‐ZTO hybrid phototransistor achieves repeatable/reproducible real‐time full‐color detection with high photosensitivity, fast phototransient speeds, and no persistent photocurrent behavior under dynamic stimulus using primary colors. It is believed that the all‐solution processed oxide/chalcogenide hybrid phototransistor with multistacked functional materials and composition‐gradient heterointerfaces will facilitate the development of cost‐efficient, ultrasensitive, fast dynamic, and full‐color visible‐light detection system.